Liquid crystal display device

ABSTRACT

In order to increase the transmittance around a pixel and to increase the brightness of the screen in an IPS mode liquid crystal display device, a pixel electrode with a slit is formed on a common electrode through an interlayer insulating film. An opening is formed in the common electrode on the outside of the end portion of the pixel electrode as seen in a plane view. Because of the presence of the opening, the electric field lines from the end portion of the pixel electrode reach the layer above the liquid crystal layer and reach further away from the end portion of the pixel electrode, so that it is possible to increase the control ability to the liquid crystal around the pixel. As a result, the pixel transmittance can be increased as a whole and the brightness of the screen can be increased.

CROSS-REFERENCE TO RELATED APPLICATIONS CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.14/573,077 filed on Dec. 17, 2014. Further, this application claimspriority from Japanese Patent Application No. 2013-260734 filed on Dec.18, 2013, the contents of which are hereby incorporated by referenceinto this application.

BACKGROUND

The present invention relates to a liquid crystal display device, andmore particularly, to an IPS mode liquid crystal display device withexcellent viewing angle characteristics and improved brightness.

A display device includes a TFT substrate in which pixels each having apixel electrode, a thin film transistor (TFT), and the like are arrangedin a matrix form. Further, there is provided a counter substrateopposite the TFT substrate, in which color filters, and the like, areformed at positions corresponding to the pixel electrodes of the TFTsubstrate. Further, a liquid crystal is interposed between the TFTsubstrate and the counter substrate. Then, an image is formed bycontrolling the transmittance of light through each pixel by the liquidcrystal molecules.

Liquid crystal display devices are flat and lightweight and have beenapplied in various fields. Small liquid crystal display devices arewidely used in mobile phones, digital still cameras (DSC), or otherportable devices. The viewing angle characteristics are a problem in theliquid crystal display device. The viewing angle characteristics are aphenomenon that the brightness or the chromaticity varies when thescreen is seen from the front and from an oblique angle. The viewingangle characteristics are excellent in the In Plane Switching (IPS) modethat drives liquid crystal molecules by an electric field in thehorizontal direction.

Among various types in the IPS mode, for example, there is a mode inwhich a common electrode is formed in a matted manner and a comb-shapedpixel electrode is provided on the common electrode with an insulatingfilm interposed therebetween, to rotate liquid crystal molecules by theelectric field generated between the pixel electrode and the commonelectrode. This type of mode can increase the transmittance and iscurrently the mainstream mode. In order to increase the transmittance ofa pixel in a liquid crystal display device having the structuredescribed above, there are structures in which the cross-sectional shapeof the common electrode is changed, such as those disclosed in PatentDocument 1 (Japanese Patent Application Laid-Open No. 2009-150952),Patent Document 2 (Japanese Patent Application Laid-Open No.2007-86576), and Patent Document 3 (Japanese Patent ApplicationLaid-Open No. 2007-240911). Further, Patent Document 4 (Japanese PatentApplication Laid-Open No. 2009-116058) describes a structure in which anopening is provided in the common electrode to adjust the capacitybetween the pixel electrode and the common electrode.

SUMMARY

FIG. 14 is a plan view of a pixel in an IPS mode liquid crystal displaydevice. In FIG. 14, a pixel is formed in an area surrounded by scanninglines 10 and video signal lines 20. A pixel electrode 110 of arectangular shape with a slit 40 is formed in the pixel. A commonelectrode 108 is formed in a planar shape below the pixel electrode 110with an interlayer insulating film interposed therebetween. When avoltage is applied to the pixel electrode 110, electric field lines aregenerated from the pixel electrode 110 towards the common electrode,passing through the liquid crystal layer and through the slit 40 or theoutside of the end portion of the pixel electrode 110.

The liquid crystal molecules are rotated by the components of theelectric field lines in the direction parallel to the plane of thesubstrate, to control the transmittance of light through the liquidcrystal layer. The density of the electric field lines is smaller in theslit 40 of the pixel electrode 110 than in the end portion of the pixelelectrode 110. The electric field lines from the pixel electrodes 110 onboth sides pass through the slit 40. However, the electric field line isonly from one side of the end portion of the pixel electrode 110. Forthis reason, the intensity of the electric field in the vicinity of thevideo signal line is very small.

Thus, the liquid crystal molecules around the pixel electrode 110 havenot been fully used and the transmittance has been insufficient in thepast. The problem to be solved by the present invention is to increasethe transmittance of pixels, that is, the brightness of the screen byfully using the liquid crystal also around the pixel electrode 110.

The present invention is made to overcome the above problems, specificmeans are as follows:

(1) There is provided a liquid crystal display device including a TFTsubstrate in which pixels each having a pixel electrode formed in anarea surrounded by scanning lines extending in a first direction andbeing arranged in a second direction, are arranged in a matrix form.Then, a liquid crystal layer is interposed between the TFT substrate anda counter substrate. A common electrode is formed in the lower layer ofthe pixel electrode through an interlayer insulating film. An openinghaving a long axis in the second direction is formed in the commonelectrode as seen in a plan view, on both outer sides of the end portionof the pixel electrode in the first direction. Then, the opening is notformed in any area other than both outer sides of the end portion of thepixel electrode in the first direction.

(2) In the liquid crystal display device described in (1), the openingdoes not overlap the video signal line as seen in a plan view.

(3) In the liquid crystal display device described in (1) or (2), thedistance between the end portion of the pixel electrode in the firstdirection, and the end portion of the opening of the common electrode onthe side far from the end portion of the pixel electrode in the firstdirection, is in the range of 0.25 to 5 μm.

(4) In the liquid crystal display device described in (3), the distancebetween the end portion of pixel electrode in the first direction, andthe end portion of the opening of the pixel electrode of the commonelectrode on the side far from the end portion in the first direction,is in the range of 0.5 to 3 μm.

(5) In the liquid crystal display device described in (1), the pixelelectrode has a slit, and the opening of the common electrode does notoverlap the slit of the pixel electrode as seen in a plan view.

(6) In the liquid crystal display device described in (5), the openingdoes not overlap the video signal line as seen in a plan view.

(7) In the liquid crystal display device described in (5) or (6), thedistance between the end portion of the pixel electrode in the firstdirection, and the end portion of the opening of the common electrode onthe side far from the end portion of the pixel electrode in the firstdirection, is in the range of 0.25 to 5 μm.

(8) In the liquid crystal display device described in (7), the distancebetween the end portion of the pixel electrode in the first direction,and the end portion of the opening of the common electrode on the sidefar from the end portion of the pixel electrode in the first direction,is in the range of 0.5 to 3 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a pixel of a liquid crystal display deviceaccording to the present invention;

FIG. 2 is a cross-sectional view of the pixel shown in FIG. 1;

FIG. 3 shows the A-A cross section of FIG. 1;

FIG. 4 is a cross-sectional view showing the principle of the presentinvention;

FIG. 5 is a cross-sectional view of a conventional example;

FIG. 6 is a comparison of the pixel transmittance in the presentinvention and in the conventional example;

FIG. 7 is a plan view showing the relationship between a pixel and anopening of the common electrode in the present invention;

FIG. 8 is a graph showing the relationship between the voltage appliedto the pixel electrode and the liquid crystal transmittance according tothe present invention;

FIG. 9 is a graph showing an example of the effect of the presentinvention;

FIG. 10 is a plan view showing an example of applying the presentinvention to a dual-domain pixel;

FIG. 11 is a plan view showing an example of applying the presentinvention to a pseudo dual-domain pixel;

FIG. 12 is a plan view of a pixel according to a second embodiment;

FIG. 13 is a cross-sectional view showing the operation of the secondembodiment; and

FIG. 14 is a plan view showing a pixel in the conventional example.

DETAILED DESCRIPTION

Hereinafter, the present invention will be described in detail withreference to embodiments.

First Embodiment

FIG. 1 is a plan view of a pixel structure according to the presentinvention. FIG. 2 is a cross-sectional view of a pixel portion, and FIG.3 is a cross-sectional view taken along line A-A of FIG. 1. First, thecross-sectional structure of FIG. 2 will be described. In FIG. 2, a gateelectrode 101 is formed on a TFT substrate 100 formed of glass. Then, agate insulating film 102 is formed so as to cover the TFT substrate 100and the gate electrode 101. A semiconductor layer 103 is formed on thegate insulating film 102 above the gate electrode 101.

The semiconductor layer 103 is formed by a-Si. A source electrode 104and a drain electrode 105 are formed facing each other on thesemiconductor layer 103 through n+a-Si, not shown. With respect to thedrain electrode and the source electrode, the names may be reversed aswell. An inorganic passivation film 106 is formed so as to cover thesemiconductor layer 103, the source electrode 104, and the drainelectrode 105. Then, an organic passivation film 107 that also functionsas a flattering film is formed on the inorganic passivation film 106.However, the inorganic passivation film may not necessarily be formed.The organic passivation film 107 is formed thick with a thickness of 1to 3 μm.

A common electrode 108 is formed by ITO in a planar shape on the organicpassivation film 107. An interlayer insulating film 109 is formed so asto cover the common electrode 108. Then, the pixel electrode 110 havingthe slit 40 is formed on the interlayer insulating film 109. The pixelelectrode 110 is coupled to the drain electrode 105 through a throughhole 130. An alignment film 111, which is used for an initial alignmentof the liquid crystal, is formed so as to cover the pixel electrode 110.In FIG. 2, when a video signal is applied to the pixel electrode 110,electric field lines are generated between the pixel electrode 110 andthe common electrode 108 as shown in the figure. Then, liquid crystalmolecules 301 are rotated by the components of the electric field linesto control the light from the backlight.

The TFT substrate and a counter substrate 200 are provided with a liquidcrystal layer 300 interposed therebetween. A color filter 201 is formedin an area corresponding to the pixel electrode 110 inside the countersubstrate 200. Then, a black matrix 202 is formed between the colorfilters 201. An overcoat film 203 is formed so as to cover the colorfilters 201 and the black matrix 202. Then, the alignment film 111 isformed on the overcoat film 203. The common electrode is not formed onthe side of the counter substrate 200, so that an external conductivefilm 210 of ITO is formed on the outside of the counter substrate 200 toshield the noise from the outside.

FIG. 2 shows a so-called bottom gate type TFT. However, there is also atop gate type TFT in which the gate electrode 102 is formed on thesemiconductor layer 103. Further, the material of the semiconductorlayer 103 is not limited to a-Si, and may also be poly-Si.

FIG. 1 is a plan view showing the pixel structure according to thepresent invention. In FIG. 1, the scanning lines 10 extend in thehorizontal direction and are arranged at a predetermined pitch. Thevideo signal lines 20 extend in the vertical direction and are arrangedat a predetermined pitch. Each of the pixels is partitioned by twoscanning lines and two video signal lines, in which the TFT, the pixelelectrode 110, and the common electrode 108 are present.

In FIG. 1, the semiconductor layer 103 is formed on the gate electrode101 branching from the scanning line 10 through the gate insulatingfilm. The source electrode 104 branching from the video signal line, andthe drain electrode 105 facing the source electrode 104 are formed onthe semiconductor layer 103. The region between the source electrode 104and the drain electrode 105 is the TFT channel region. The drainelectrode 105 is electrically coupled to the pixel electrode 110 throughthe through hole 130 to provide a video signal to the pixel electrode110.

The common electrode 108 is formed in a planar shape below the pixelelectrode 110 as described in FIG. 2. When a signal voltage is appliedto the pixel electrode 110, as shown in FIG. 2, the electric field linespass through the liquid crystal layer 300 to reach the common electrode108, through the slit 40 of the pixel electrode 110 and through theoutside of the pixel electrode 110 (between the end portion of the pixelelectrode on the side of the adjacent video signal line, and theadjacent video signal line). The liquid crystal is rotated by theelectric field lines to control the transmittance of the liquid crystallayer.

The feature of the present invention is that the slit-like opening 30(hereinafter also referred to as the opening) is formed in the commonelectrode 108 on both sides of the pixel electrode 110. The electricfield lines from the end portion of the pixel electrode 110 can reachfurther away and expand the area to control the liquid crystal, becausethe opening 30 is formed. Thus, the transmittance around the pixel canbe increased. As a result, the brightness of the screen can beincreased.

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1. In FIG.3, the gate insulating film 102 is formed on the TFT substrate 100, andthe video signal line 20 extends in the direction perpendicular to thepaper, on the gate insulating film 102. The inorganic passivation film106 is formed so as to cover the video signal line 20. The organicpassivation film 107 is formed on the inorganic passivation film 106.Then, the opening 30 of the common electrode 108 is formed in aslit-like shape at positions corresponding to both sides of the videosignal line 20.

The interlayer insulating film 109 is formed so as to cover the commonelectrode 108. Then, the pixel electrode 110 with the slit 40 is formedon the interlayer insulating film 109. The feature of the presentinvention is that the opening 30 is formed in the common electrode 108on both sides above the video signal line 20. Because of this opening30, it is possible to increase the transmittance of the liquid crystalon the outside of the pixel electrode 110, in other words, on both sidesof the video signal line 20. In FIG. 3, the width of the commonelectrode 108 on the video signal line 20 is greater than the width ofthe video signal line 20. In other words, the opening 30 of the commonelectrode 108 preferably should not overlap the video signal line 20 asseen in a plane view. This is to allow the common electrode 108 toshield the video signal passing through the video signal line 20.

FIG. 5 is a cross-sectional view showing the state of the electric fieldlines between the pixel electrode 110 and the common electrode 108within the pixel in the existing structure. In FIG. 5, the electricfield lines from the pixel electrode 110 extend to the common electrode108. The electric field lines are formed on both sides of the pixelelectrode 110 at a position corresponding to the slit 40 of the pixelelectrode 110. However, the electric field lines are formed only on oneside of the end portion of the pixel electrode 110. Thus, in theexisting structure, the liquid crystal molecules may not be completelydriven on the outside of the pixel electrode 110.

FIG. 4 is a cross-sectional view of the present invention. FIG. 4 isdifferent from FIG. 5 in that the slit-like opening 30 is formed in thecommon electrode 108 at a position corresponding to the outside of thepixel electrode 110. The electric field lines from the end portion ofthe pixel electrode 110 pass through the layer above the liquid crystallayer 300, and reaches the remote common electrode 108, because theopening 30 is formed as described above. In this way, it is possible todrive the liquid crystal molecules 30 on the outside of the pixelelectrode 110 more effectively than before. As a result, the pixeltransmittance can be increased.

FIG. 6 is a graph showing the difference in the pixel transmittancebetween when the opening 30 is formed in the common electrode 108 andwhen it is not. In FIG. 6, three slits are formed in the pixel electrode110. In FIG. 6, the slide curve line represents the case of the presentinvention, in which the common electrode 108 is formed on the outside ofthe pixel electrode 110. In FIG. 6, the dotted curve line represents thecase of the existing structure, in which no opening is formed in thecommon electrode 108. As shown in FIG. 6, according to the presentinvention, the transmittance on the outside of the pixel electrode 110is increased to an amount greater than that in the existing structure.The pixel transmittance can be increased by this amount.

FIG. 7 is a plan view showing the details of the relationship betweenthe pixel electrode 110 and the common electrode 108 according to thepresent invention. Note that the interlayer insulating film is formedbetween the pixel electrode 110 and the common electrode 108. Theopening 30 of the common electrode 108 is formed parallel to the slit 40of the pixel electrode 110 on the outside of the pixel electrode 110, asseen in a plan view. Preferably, the end portion of the opening 30 ofthe common electrode 108 on the side of the pixel electrode 110 matchesthe end portion of the pixel electrode 110, as seen in a plane view. Thedistance from the end portion of the pixel electrode 110 to the endportion of the opening 30 of the common electrode 108 on the side farfrom the pixel electrode 110 is x1. The value of x1 is set in the rangeof 0.25 to 5 μm, and more preferably, in the range of 0.5 to 3 μm.

However, due to the deviation in the alignment of a photomask, theopening 30 of the common electrode 108 may be displaced to the side ofthe pixel electrode 110 by x2, or may be displaced to the outside of thepixel electrode 110 by x3. If the end portion of the opening 30 ispresent inside the pixel electrode 110, the capacity of the pixel isreduced. On the other hand, if the end portion of the opening 30 on theside of the pixel electrode 110 is displaced to the outside away fromthe pixel electrode 110, the effect of the present invention is reduced.By taking into account the deviation in the photomask alignment, thedistance between the end portions of the slit on the pixel electrodeside, may also be made smaller than the distance between the outside endportions of the pixel electrode, that is, than the width of the pixelelectrode.

Also in FIG. 7, preferably the end portion of the opening 30 of thecommon electrode 108 does not overlap the slit 40 of the pixel electrode110 as seen in a plan view, even if the end portion of the opening 30 ofthe common electrode 108 is displaced to the inside of the pixelelectrode 110. This is because the pixel capacity is significantlyreduced when the end portion of the opening of the common electrode 108is displayed to the extent that it overlaps the slit 40 of the pixelelectrode 110.

In FIG. 7, when c1 is the length of the slit 40 of the pixel electrode110, and when b1 is the length of the opening 30 of the common electrode108, the relationship is given as c1≥b1. Further, when c2 is thedistance from the end portion of the pixel electrode 110 to the endportion in the length direction of the slit 40, and when b2 is thedistance from the end portion of the pixel electrode 110 to the endportion in the direction of the long axis of the opening 30 of thecommon electrode 108, the relationship is given as b2≥c2.

The feature of the present invention is that the opening 30 of thecommon electrode 108 is formed only on the outside of the pixelelectrode 110 as seen in a plan view, and is not formed in the slitportion of the pixel electrode. In other words, only one opening 30 isformed on each of both sides of one pixel electrode 110. Even if theopening 30 is formed in the common electrode 108 on the inside of thepixel electrode 110 as seen in a plan view, there may be little effectof increasing the brightness. On the other hand, if the opening 30 ofthe common electrode 108 is formed on the inside of the pixel electrode110 as seen in a plan view, the pixel capacity will be reduced.

FIG. 8 is a graph showing the change in the transmittance of the liquidcrystal layer, upon changing the distance x1 from the end portion of thepixel electrode 110 to the end portion of the opening 30 of the commonelectrode 108 on the side far from the pixel electrode 110. In FIG. 8,the horizontal axis is the voltage between the pixel electrode 110 andthe common electrode 108, and the vertical axis is the transmittance ofthe liquid crystal layer. In FIG. 8, the greater the distance x1 fromthe end portion of the pixel electrode 110 to the end portion of theopening 30 of the common electrode 108 on the side far from the pixelelectrode 110, the greater the maximum value of the transmittance.However, the greater the value of x1, the more the voltage to maximizethe transmittance is shifted to the high voltage side.

FIG. 9 is a graph of the comparison of the transmittance with c1=50 μm,b1=30 μm, and x1=1.5 μm, between the pixel structure shown in FIG. 7 andthe existing structure. In FIG. 9, the horizontal axis represents thespecifications of the present invention and the existing structure, thatis, the presence or absence of the opening of the common electrode,while the vertical axis represents the pixel transmittance. In the caseof the present invention, the transmittance is increased by 7% comparedto the existing structure. In this way, the effect of the presentinvention is very large.

The IPS mode liquid crystal display device has excellent viewing anglecharacteristics. However, the viewing angle characteristics may varydepending on the azimuth angle, that is, the direction in which thescreen is seen. In order to address this problem, there is a structurein which the angles of the slits of the pixel electrode with thealignment axis of the alignment film are different in one pixel. In thiscase, two domains are formed in one pixel and this structure is called adual domain. The present invention can also be applied to the pixel ofthis structure.

FIG. 10 is an example of applying the present invention to a dual domainpixel. In FIG. 10, the pixel electrode 110 and the slit 40, which isformed inside of the pixel electrode 110, are curved in the y directionin a central portion. The direction of the alignment axis is the ydirection. The angles of the long axis direction with the alignment axison the upper and lower sides of the pixel are in an inverserelationship. In other words, the viewing angle characteristics on theupper and lower sides of the pixel are reversed in the y direction ofthe pixel. Thus, the viewing angle characteristics are equalized. Thevideo signal lines 20 are curved in the y direction in a central portionof the pixel along with the pixel electrode 110.

The present invention can also be applied to such a dual domain pixel.In FIG. 10, the opening 30 of the common electrode 108 is formed on bothsides of the pixel electrode 110. The opening 30 of the common electrode108 is also curved in the y direction in a central portion along theshape of the pixel electrode 110. Others are the same as those describedin FIGS. 6 to 9, except the opening 30 is curved.

FIG. 11 is an example of applying the present invention to a method forcombining two pixels to equalize the azimuth characteristics of theviewing angle of the IPS mode liquid crystal display device. Such apixel structure is referred to as a pseudo dual-domain pixel. In thepixel shown in FIG. 11, the pixel electrode 110 and the slits 40 aretilted at a predetermined angle with respect to the y axis direction. Onthe other hand, the pixel electrodes 110 and the slits 40 in the pixelsin the y direction above and below the particular pixel are tilted in adirection reverse to the y axis direction. This makes it possible toequalize the azimuth characteristics of the viewing angle of the screenas a whole. This is called a pseudo dual-domain mode. The advantage ofFIG. 11 is that there is one domain because the liquid crystal moleculesin the pixel are rotated in the same direction, so that a significantdisclination does not appear in the pixel.

The present invention can also be applied to the liquid crystal displaydevice of such a pseudo dual-domain mode. In FIG. 11, the opening 30 ofthe common electrode 108 is formed on both sides of the pixel electrode110. Similar to the pixel electrode 110, the opening 30 of the commonelectrode 108 is also tilted at a predetermined angle with respect tothe y axis direction. Others are the same as those described in FIGS. 6to 9.

In the foregoing description, it has been assumed that the number ofslits 40 in the pixel electrode 110 is three, that is, the pixelelectrode has the comb-like portion of four teeth. However, the preventinvention can also be applied when the number of slits 40 in the pixelelectrode 110 is one, that is, the pixel electrode has a comb-likeportion of two teeth, or when the pixel electrode 110 has multiple slits40. Note that in the present specification, it is assumed that thedirection of the alignment axis is the y axis direction. However, it isalso possible that the alignment axis is the x direction by using anegative type liquid crystal instead of a positive type liquid crystal.

Second Embodiment

FIG. 12 is a plan view of a pixel showing a second embodiment of thepresent invention. The feature of FIG. 12 is that the pixel electrode110 has a comb-like portion of one tooth and has no slit. As the screenis high definition, the width of the pixel electrode may become toosmall to form a slit in the pixel electrode 110. The present inventioncan also be applied to such a pixel structure.

In FIG. 12, a pixel is formed in an area surrounded by the scanninglines 10 and the video signal lines 20. The TFT is formed in the ydirection below the pixel. The pixel electrode 110 is coupled to the TFTthrough the through hole 130. The pixel electrode 110 extends in astrip-like shape in the y axis direction. In such a structure, theliquid crystal molecules are controlled only by the electric field linesextending from the end portion of the pixel electrode 110 to the lowerlayer of the common electrode 108. For this reason, the control abilityto the liquid crystal layer is smaller than that of the electric fieldlines extending to the common electrode through the slit of the pixelelectrode 110.

Accordingly, in the present embodiment, the opening 30 of the commonelectrode 108 is formed on both sides of the pixel electrode 110 with noslit, to allow the electric field lines to penetrate into the layerabove the liquid crystal layer, and to allow the electric field lines toreach further away from the pixel electrode 110. In this way, it ispossible to increase the control ability to the liquid crystal layer.

FIG. 13 is a cross-sectional view showing this state. FIG. 13corresponds to a cross-sectional view taken along line B-B of FIG. 12.In FIG. 13, the dashed line shows the state of the electric field lineswhen there is no opening in the common electrode 108 as in the existingstructure. The solid line shows the electric filed lines when theopening 30 is present in the common electrode 108 as in the presentembodiment. As shown clearly in FIG. 13, the electric field lines reachthe layer above the liquid crystal layer 300, and reach further awayfrom the end portion of the pixel electrode 110, because the opening 30is present in the common electrode 108. Thus, it is possible to operatethe liquid crystal molecules more effectively and to increase the pixeltransmittance. Further, the common electrode 108 is formed below thepixel electrode 110, so that the retention volume can be ensured.

The detailed structure of forming the opening 30 of the common electrode108 on both sides of the pixel electrode 110 with no slit, as well asthe effect of such a structure are the same as described in FIGS. 6 to9. Note that in the present specification, the pixel electrode 110 andthe common electrode 108 are formed by a transparent conductive film,for example, by ITO or IZO.

As described above, the present invention can increase the pixeltransmittance. As a result, the brightness of the screen can beincreased.

What is claimed is:
 1. A display device comprising: a TFT substratehaving scanning lines extending in a first direction, video signal linesextending in a second direction crossing the first direction, a firstelectrode overlapped with the scanning lines and the video signal lines,an insulating film formed on the first electrode, and a second electrodeformed on the insulating film overlapping with the first electrode; anda counter substrate opposed to the TFT substrate; wherein the secondelectrode is formed in an area surrounded by the scanning lines and thevideo lines, the first electrode has an opening formed in the area, theopening is formed along the second electrode and an edge of the openingin the first direction is apart from the second electrode, in a planview, and the edge of the opening is between the second electrode andthe video signal lines, in a plan view.
 2. The display device accordingto claim 1, wherein the distance is in the range of 0.25 μm to 5 μm. 3.The display device according to claim 1, wherein the distance is in therange of 0.5 μm to 3 μm.
 4. The display device according to claim 1,wherein the opening does not overlap the video signal line as seen in aplan view.
 5. The display device according to claim 1, wherein theopening does not overlap the scanning line as seen in a plan view. 6.The display device according to claim 1, wherein the opening is formedbetween the video signal line and the second electrode, wherein a partof the opening overlaps with the second electrode.
 7. The display deviceaccording to claim 1, wherein the second electrode is a line shapeelectrode and does not have a slit.
 8. The display device according toclaim 1, wherein the opening does not overlap with the second electrode,in a plan view.
 9. The display device according to claim 8, wherein theopening includes a first opening and a second opening, and the secondelectrode is between the first opening and the second opening, in a planview.
 10. The display device according to claim 9, wherein the secondelectrode opposes to the first electrode between the first opening andthe second opening.
 11. The display device according to claim 1, whereinthe TFT substrate has a thin film transistor in the area, and the secondelectrode is connected to the thin film transistor through a throughhole.
 12. The display device according to claim 11, wherein the firstelectrode has a hole corresponding to the through hole, and the hole andthe opening are not connected.